I got in touch with support and we sorted things out after trying various things.

After the initial set of things we tried and then performing "cf login" interactively, we got a reasonable error message. After running "cf login" I enter the email associated with my IBM ID when it prompts for email, but I can't login ("No such account"). However if I enter my IBM ID (userid) when it prompts for email, I can login fine. This appears to be a defect. We think this occurs when your userid and email are different (which is apparently not that common).